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136504195a
curl/lib/hsts.c
Daniel Stenberg ba235ab269
llist: remove direct struct accesses, use only functions 
- Turned them all into functions to also do asserts etc.

- The llist related structs got all their fields renamed in order to make
  sure no existing code remains using direct access.

- Each list node struct now points back to the list it "lives in", so
  Curl_node_remove() no longer needs the list pointer.

- Rename the node struct and some of the access functions.

- Added lots of ASSERTs to verify API being used correctly

- Fix some cases of API misuse

Add docs/LLIST.md documenting the internal linked list API.

Closes #14485
2024-08-12 13:18:10 +02:00

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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* SPDX-License-Identifier: curl
*
***************************************************************************/
/*
* The Strict-Transport-Security header is defined in RFC 6797:
* https://datatracker.ietf.org/doc/html/rfc6797
*/
#include "curl_setup.h"
#if !defined(CURL_DISABLE_HTTP) && !defined(CURL_DISABLE_HSTS)
#include <curl/curl.h>
#include "urldata.h"
#include "llist.h"
#include "hsts.h"
#include "curl_get_line.h"
#include "strcase.h"
#include "sendf.h"
#include "strtoofft.h"
#include "parsedate.h"
#include "fopen.h"
#include "rename.h"
#include "share.h"
#include "strdup.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"
#define MAX_HSTS_LINE 4095
#define MAX_HSTS_HOSTLEN 256
#define MAX_HSTS_HOSTLENSTR "256"
#define MAX_HSTS_DATELEN 64
#define MAX_HSTS_DATELENSTR "64"
#define UNLIMITED "unlimited"
#if defined(DEBUGBUILD) || defined(UNITTESTS)
/* to play well with debug builds, we can *set* a fixed time this will
return */
time_t deltatime; /* allow for "adjustments" for unit test purposes */
static time_t hsts_debugtime(void *unused)
{
char *timestr = getenv("CURL_TIME");
(void)unused;
if(timestr) {
curl_off_t val;
(void)curlx_strtoofft(timestr, NULL, 10, &val);
val += (curl_off_t)deltatime;
return (time_t)val;
}
return time(NULL);
}
#undef time
#define time(x) hsts_debugtime(x)
#endif
struct hsts *Curl_hsts_init(void)
{
struct hsts *h = calloc(1, sizeof(struct hsts));
if(h) {
Curl_llist_init(&h->list, NULL);
}
return h;
}
static void hsts_free(struct stsentry *e)
{
free((char *)e->host);
free(e);
}
void Curl_hsts_cleanup(struct hsts **hp)
{
struct hsts *h = *hp;
if(h) {
struct Curl_llist_node *e;
struct Curl_llist_node *n;
for(e = Curl_llist_head(&h->list); e; e = n) {
struct stsentry *sts = Curl_node_elem(e);
n = Curl_node_next(e);
hsts_free(sts);
}
free(h->filename);
free(h);
*hp = NULL;
}
}
static CURLcode hsts_create(struct hsts *h,
const char *hostname,
bool subdomains,
curl_off_t expires)
{
size_t hlen;
DEBUGASSERT(h);
DEBUGASSERT(hostname);
hlen = strlen(hostname);
if(hlen && (hostname[hlen - 1] == '.'))
/* strip off any trailing dot */
--hlen;
if(hlen) {
char *duphost;
struct stsentry *sts = calloc(1, sizeof(struct stsentry));
if(!sts)
return CURLE_OUT_OF_MEMORY;
duphost = Curl_memdup0(hostname, hlen);
if(!duphost) {
free(sts);
return CURLE_OUT_OF_MEMORY;
}
sts->host = duphost;
sts->expires = expires;
sts->includeSubDomains = subdomains;
Curl_llist_append(&h->list, sts, &sts->node);
}
return CURLE_OK;
}
CURLcode Curl_hsts_parse(struct hsts *h, const char *hostname,
const char *header)
{
const char *p = header;
curl_off_t expires = 0;
bool gotma = FALSE;
bool gotinc = FALSE;
bool subdomains = FALSE;
struct stsentry *sts;
time_t now = time(NULL);
if(Curl_host_is_ipnum(hostname))
/* "explicit IP address identification of all forms is excluded."
/ RFC 6797 */
return CURLE_OK;
do {
while(*p && ISBLANK(*p))
p++;
if(strncasecompare("max-age=", p, 8)) {
bool quoted = FALSE;
CURLofft offt;
char *endp;
if(gotma)
return CURLE_BAD_FUNCTION_ARGUMENT;
p += 8;
while(*p && ISBLANK(*p))
p++;
if(*p == '\"') {
p++;
quoted = TRUE;
}
offt = curlx_strtoofft(p, &endp, 10, &expires);
if(offt == CURL_OFFT_FLOW)
expires = CURL_OFF_T_MAX;
else if(offt)
/* invalid max-age */
return CURLE_BAD_FUNCTION_ARGUMENT;
p = endp;
if(quoted) {
if(*p != '\"')
return CURLE_BAD_FUNCTION_ARGUMENT;
p++;
}
gotma = TRUE;
}
else if(strncasecompare("includesubdomains", p, 17)) {
if(gotinc)
return CURLE_BAD_FUNCTION_ARGUMENT;
subdomains = TRUE;
p += 17;
gotinc = TRUE;
}
else {
/* unknown directive, do a lame attempt to skip */
while(*p && (*p != ';'))
p++;
}
while(*p && ISBLANK(*p))
p++;
if(*p == ';')
p++;
} while(*p);
if(!gotma)
/* max-age is mandatory */
return CURLE_BAD_FUNCTION_ARGUMENT;
if(!expires) {
/* remove the entry if present verbatim (without subdomain match) */
sts = Curl_hsts(h, hostname, FALSE);
if(sts) {
Curl_node_remove(&sts->node);
hsts_free(sts);
}
return CURLE_OK;
}
if(CURL_OFF_T_MAX - now < expires)
/* would overflow, use maximum value */
expires = CURL_OFF_T_MAX;
else
expires += now;
/* check if it already exists */
sts = Curl_hsts(h, hostname, FALSE);
if(sts) {
/* just update these fields */
sts->expires = expires;
sts->includeSubDomains = subdomains;
}
else
return hsts_create(h, hostname, subdomains, expires);
return CURLE_OK;
}
/*
* Return TRUE if the given hostname is currently an HSTS one.
*
* The 'subdomain' argument tells the function if subdomain matching should be
* attempted.
*/
struct stsentry *Curl_hsts(struct hsts *h, const char *hostname,
bool subdomain)
{
if(h) {
char buffer[MAX_HSTS_HOSTLEN + 1];
time_t now = time(NULL);
size_t hlen = strlen(hostname);
struct Curl_llist_node *e;
struct Curl_llist_node *n;
if((hlen > MAX_HSTS_HOSTLEN) || !hlen)
return NULL;
memcpy(buffer, hostname, hlen);
if(hostname[hlen-1] == '.')
/* remove the trailing dot */
--hlen;
buffer[hlen] = 0;
hostname = buffer;
for(e = Curl_llist_head(&h->list); e; e = n) {
struct stsentry *sts = Curl_node_elem(e);
n = Curl_node_next(e);
if(sts->expires <= now) {
/* remove expired entries */
Curl_node_remove(&sts->node);
hsts_free(sts);
continue;
}
if(subdomain && sts->includeSubDomains) {
size_t ntail = strlen(sts->host);
if(ntail < hlen) {
size_t offs = hlen - ntail;
if((hostname[offs-1] == '.') &&
strncasecompare(&hostname[offs], sts->host, ntail))
return sts;
}
}
if(strcasecompare(hostname, sts->host))
return sts;
}
}
return NULL; /* no match */
}
/*
* Send this HSTS entry to the write callback.
*/
static CURLcode hsts_push(struct Curl_easy *data,
struct curl_index *i,
struct stsentry *sts,
bool *stop)
{
struct curl_hstsentry e;
CURLSTScode sc;
struct tm stamp;
CURLcode result;
e.name = (char *)sts->host;
e.namelen = strlen(sts->host);
e.includeSubDomains = sts->includeSubDomains;
if(sts->expires != TIME_T_MAX) {
result = Curl_gmtime((time_t)sts->expires, &stamp);
if(result)
return result;
msnprintf(e.expire, sizeof(e.expire), "%d%02d%02d %02d:%02d:%02d",
stamp.tm_year + 1900, stamp.tm_mon + 1, stamp.tm_mday,
stamp.tm_hour, stamp.tm_min, stamp.tm_sec);
}
else
strcpy(e.expire, UNLIMITED);
sc = data->set.hsts_write(data, &e, i,
data->set.hsts_write_userp);
*stop = (sc != CURLSTS_OK);
return sc == CURLSTS_FAIL ? CURLE_BAD_FUNCTION_ARGUMENT : CURLE_OK;
}
/*
* Write this single hsts entry to a single output line
*/
static CURLcode hsts_out(struct stsentry *sts, FILE *fp)
{
struct tm stamp;
if(sts->expires != TIME_T_MAX) {
CURLcode result = Curl_gmtime((time_t)sts->expires, &stamp);
if(result)
return result;
fprintf(fp, "%s%s \"%d%02d%02d %02d:%02d:%02d\"\n",
sts->includeSubDomains ? ".": "", sts->host,
stamp.tm_year + 1900, stamp.tm_mon + 1, stamp.tm_mday,
stamp.tm_hour, stamp.tm_min, stamp.tm_sec);
}
else
fprintf(fp, "%s%s \"%s\"\n",
sts->includeSubDomains ? ".": "", sts->host, UNLIMITED);
return CURLE_OK;
}
/*
* Curl_https_save() writes the HSTS cache to file and callback.
*/
CURLcode Curl_hsts_save(struct Curl_easy *data, struct hsts *h,
const char *file)
{
struct Curl_llist_node *e;
struct Curl_llist_node *n;
CURLcode result = CURLE_OK;
FILE *out;
char *tempstore = NULL;
if(!h)
/* no cache activated */
return CURLE_OK;
/* if no new name is given, use the one we stored from the load */
if(!file && h->filename)
file = h->filename;
if((h->flags & CURLHSTS_READONLYFILE) || !file || !file[0])
/* marked as read-only, no file or zero length filename */
goto skipsave;
result = Curl_fopen(data, file, &out, &tempstore);
if(!result) {
fputs("# Your HSTS cache. https://curl.se/docs/hsts.html\n"
"# This file was generated by libcurl! Edit at your own risk.\n",
out);
for(e = Curl_llist_head(&h->list); e; e = n) {
struct stsentry *sts = Curl_node_elem(e);
n = Curl_node_next(e);
result = hsts_out(sts, out);
if(result)
break;
}
fclose(out);
if(!result && tempstore && Curl_rename(tempstore, file))
result = CURLE_WRITE_ERROR;
if(result && tempstore)
unlink(tempstore);
}
free(tempstore);
skipsave:
if(data->set.hsts_write) {
/* if there is a write callback */
struct curl_index i; /* count */
i.total = Curl_llist_count(&h->list);
i.index = 0;
for(e = Curl_llist_head(&h->list); e; e = n) {
struct stsentry *sts = Curl_node_elem(e);
bool stop;
n = Curl_node_next(e);
result = hsts_push(data, &i, sts, &stop);
if(result || stop)
break;
i.index++;
}
}
return result;
}
/* only returns SERIOUS errors */
static CURLcode hsts_add(struct hsts *h, char *line)
{
/* Example lines:
example.com "20191231 10:00:00"
.example.net "20191231 10:00:00"
*/
char host[MAX_HSTS_HOSTLEN + 1];
char date[MAX_HSTS_DATELEN + 1];
int rc;
rc = sscanf(line,
"%" MAX_HSTS_HOSTLENSTR "s \"%" MAX_HSTS_DATELENSTR "[^\"]\"",
host, date);
if(2 == rc) {
time_t expires = strcmp(date, UNLIMITED) ? Curl_getdate_capped(date) :
TIME_T_MAX;
CURLcode result = CURLE_OK;
char *p = host;
bool subdomain = FALSE;
struct stsentry *e;
if(p[0] == '.') {
p++;
subdomain = TRUE;
}
/* only add it if not already present */
e = Curl_hsts(h, p, subdomain);
if(!e)
result = hsts_create(h, p, subdomain, expires);
else {
/* the same hostname, use the largest expire time */
if(expires > e->expires)
e->expires = expires;
}
if(result)
return result;
}
return CURLE_OK;
}
/*
* Load HSTS data from callback.
*
*/
static CURLcode hsts_pull(struct Curl_easy *data, struct hsts *h)
{
/* if the HSTS read callback is set, use it */
if(data->set.hsts_read) {
CURLSTScode sc;
DEBUGASSERT(h);
do {
char buffer[MAX_HSTS_HOSTLEN + 1];
struct curl_hstsentry e;
e.name = buffer;
e.namelen = sizeof(buffer)-1;
e.includeSubDomains = FALSE; /* default */
e.expire[0] = 0;
e.name[0] = 0; /* just to make it clean */
sc = data->set.hsts_read(data, &e, data->set.hsts_read_userp);
if(sc == CURLSTS_OK) {
time_t expires;
CURLcode result;
DEBUGASSERT(e.name[0]);
if(!e.name[0])
/* bail out if no name was stored */
return CURLE_BAD_FUNCTION_ARGUMENT;
if(e.expire[0])
expires = Curl_getdate_capped(e.expire);
else
expires = TIME_T_MAX; /* the end of time */
result = hsts_create(h, e.name,
/* bitfield to bool conversion: */
e.includeSubDomains ? TRUE : FALSE,
expires);
if(result)
return result;
}
else if(sc == CURLSTS_FAIL)
return CURLE_ABORTED_BY_CALLBACK;
} while(sc == CURLSTS_OK);
}
return CURLE_OK;
}
/*
* Load the HSTS cache from the given file. The text based line-oriented file
* format is documented here: https://curl.se/docs/hsts.html
*
* This function only returns error on major problems that prevent hsts
* handling to work completely. It will ignore individual syntactical errors
* etc.
*/
static CURLcode hsts_load(struct hsts *h, const char *file)
{
CURLcode result = CURLE_OK;
FILE *fp;
/* we need a private copy of the filename so that the hsts cache file
name survives an easy handle reset */
free(h->filename);
h->filename = strdup(file);
if(!h->filename)
return CURLE_OUT_OF_MEMORY;
fp = fopen(file, FOPEN_READTEXT);
if(fp) {
struct dynbuf buf;
Curl_dyn_init(&buf, MAX_HSTS_LINE);
while(Curl_get_line(&buf, fp)) {
char *lineptr = Curl_dyn_ptr(&buf);
while(*lineptr && ISBLANK(*lineptr))
lineptr++;
/*
* Skip empty or commented lines, since we know the line will have a
* trailing newline from Curl_get_line we can treat length 1 as empty.
*/
if((*lineptr == '#') || strlen(lineptr) <= 1)
continue;
hsts_add(h, lineptr);
}
Curl_dyn_free(&buf); /* free the line buffer */
fclose(fp);
}
return result;
}
/*
* Curl_hsts_loadfile() loads HSTS from file
*/
CURLcode Curl_hsts_loadfile(struct Curl_easy *data,
struct hsts *h, const char *file)
{
DEBUGASSERT(h);
(void)data;
return hsts_load(h, file);
}
/*
* Curl_hsts_loadcb() loads HSTS from callback
*/
CURLcode Curl_hsts_loadcb(struct Curl_easy *data, struct hsts *h)
{
if(h)
return hsts_pull(data, h);
return CURLE_OK;
}
void Curl_hsts_loadfiles(struct Curl_easy *data)
{
struct curl_slist *l = data->state.hstslist;
if(l) {
Curl_share_lock(data, CURL_LOCK_DATA_HSTS, CURL_LOCK_ACCESS_SINGLE);
while(l) {
(void)Curl_hsts_loadfile(data, data->hsts, l->data);
l = l->next;
}
Curl_share_unlock(data, CURL_LOCK_DATA_HSTS);
}
}
#endif /* CURL_DISABLE_HTTP || CURL_DISABLE_HSTS */
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